The semiconductor manufacturing industry is constantly seeking to improve the processes used to manufacture microelectronic circuits and components, such as the manufacture of integrated circuits from wafers. The objectives of many of these improved processes are decreasing the amount of time required to process a wafer to form the desired integrated circuits; increasing the yield of usable integrated circuits per wafer by, for example, decreasing contamination of the wafer during processing; reducing the number of steps required to create the desired integrated circuits; improving the uniformity and efficiency of processes used to create the desired integrated circuits; and reducing the costs of manufacture.
In the processing of wafers, it is often necessary to subject one or more sides of the wafer to a fluid in liquid, vapor or gaseous form. Such fluids are used to, for example, etch the wafer surface, clean the wafer surface, dry the wafer surface, passivate the wafer surface, deposit films on the wafer surface, etc. Controlling how the processing fluids are applied to the wafer surfaces is often important to the success of the processing operations.
Various machines and methods have been used for carrying out these manufacturing processes. However, existing machines have several disadvantages. These disadvantages include relatively large consumption of process chemicals and water. This consumption of process chemicals increases manufacturing costs, which ultimately increases the cost of the final product, such as e.g., computers, cell phones, and virtually all types of consumer, industrial, commercial and military electronic products. In addition, many process chemicals are toxic and require special handling, storage, and disposal methods. These can be costly and difficult, but are necessary for health, safety and environmental reasons. Consequently, reducing consumption of process chemicals has many advantages.
In many process manufacturing steps, the process chemicals used should be applied evenly onto the wafers to avoid having too much or too little etching, film removal, etc. Existing machines often are not able to sufficiently uniformly apply process chemicals. This can result in lower yields. Moreover, many existing machines try to compensate for variations in applying process chemicals by using larger amounts of process chemicals. This inefficient use of process chemicals leads to the disadvantages described above. Accordingly, improved machines and methods which provide improved yield, consume less process chemicals and water, and offer better results in performing manufacturing operations, are needed.
Manufacturing semiconductor and similar products on a commercial scale requires a fab or manufacturing facility often costing hundreds of million dollars to build and equip. Operating and maintenance costs are also very high. Consequently, the output or yield of the fab is critical to successful operations. Faster processing can help increase the fab output. While conventional processing with liquids may produce the desired results, it can be time consuming. Accordingly, faster process methods and machines are very advantageous.
In the past, the use of sonic energy to expedite and provide more efficient processing of semiconductor products has been explored. For example, U.S. Pat. Nos. 6,492,284 and 6,511,914 disclose reactors for processing semiconductor wafers using sonic energy. The use of sonic energy in process fluids creates cavitation, i.e., the formation of partial vacuums in the process fluid. Cavitation dislodges particles and cleans the crevices created by microelectronics formed on the workpiece surface. The required concentration of the processing fluid, e.g., hydrofluoric acid, can be greatly reduced by using higher levels of sonic energy in a semiconductor surface treatment process. Further, the higher the level of sonic energy used, the greater likelihood there is of dislodging particles and impurities that could get lodged in the minute crevices created by the microelectronics formed on the wafer surface. By using more sonic energy, a more uniform and efficient process treatment can be accomplished across substantially the entire surface of the wafer being treated. Too much sonic energy, however, and the microelectronics, the wafer itself, and any dielectric on the wafer surface could be destroyed. Thus, a problem exists in the semiconductor processing industry of balancing the benefits of using sonic energy, without damaging the wafers and microelectronics.
The sonic energy sources disclosed in U.S. Pat. Nos. 6,492,284 and 6,511,914 provide a localized, highly concentrated sonic energy. The sonic energy sources disclosed in U.S. Pat. Nos. 6,492,284 and 6,511,914 do not have a total surface area corresponding to at least 25% of the total surface area of the workpiece being treated. As a result, it is difficult to achieve a uniform process treatment across the entire surface of the wafer. Moreover, the configuration of the sonic energy sources disclosed in U.S. Pat. Nos. 6,492,284 and 6,511,914: (1) create a dampening effect by trapping the sonic energy between the source and the wafer, reducing the effectiveness of the sonic energy; and (2) make it difficult to adequately drain chemistry or liquid from the bowl. The present invention is an improvement over the reactors disclosed in U.S. Pat. Nos. 6,492,284 and 6,511,914 and provide for the benefits associated with the use of sonic energy for treating semiconductor wafers, without otherwise damaging or destroying the wafer and microstructures created thereon.